Macrophage interactions with Candida.

The monocyte/macrophage, in comparison to the neutrophil, would appear to have a limited role in protection against C. albicans. This statement is based on the observations of several investigators who report that these cells have very little killing capacity unless they are activated by cytokines such as IFN-gamma and GM-CSF. The mechanisms of killing by these cells appear to include both oxidative and nonoxidative mechanisms, the latter perhaps being more important. The mechanisms of killing may be different for monocytes and macrophages. Granulocyte-macrophage colony-stimulating factor and its effect on monocytes has been studied using Candida as a target organism. Two explanations for the enhancement of monocyte killing by this cytokine have been proposed: GM-CSF augments both superoxide anion and the level of mannose receptors on treated monocytes. Both of these changes could be significant in the increased killing capacity of these cells.